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INDUSTRIAL A N D ENGINEERING CHEMISTRY
Vol. 18, No. 1
BOOK REVIEWS Gems and Gem Materials. BY EDWARD HENRYKRAUSAND EDWARD FULLER HOLDEN. 1st edition. vii 222 pages. Illustrated. 16 X 24 X 2.25 cm. Cloth. McGraw-Hill Book Co., Inc., New York, 1925. Price, $3.00.
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This splendid new work on gems now affords the reading public an opportunity t o sit in on the course of lectures annually given by Professor Kraus a t Michigan and learn from him how t o distinguish the true from the false, the artificial from the natural gem material. This is a rare privilege, as there are very few such courses given in this country and fewer masters of the subject who can put into it what Professor Kraus affords of inspiration and interest as well as of fact and subject matter. This is a book of parts, both figuratively and literally, and in the latter sense Part I deals with the necessary background of optics, crystallography, etc., with occurrence, formation, naming, cutting, and polishing of gems, and with manufactured stones. Part I1 affords a detailed description of each of the many precious and semi-precious stones and with the ornamental stones, and gives a classification of gem materials according to various properties. The latter part of the book contains many useful tables of properties of gems. Sir John Mandeville said more than half a millennium ago, “If a man would buy the diamond it is needful that he know them.” “Caveat Emptor” has not entirely been shorn of its significance. Moral, buy this book. FRANK B. WADE The Chemical Action of Ultra-Violet Rays. BY CARLETON ELLIS AND ALPRED A. WELLS. 362 pages. Illustrated. The Chemical Catalog Co., New York, 1925. Price, $5.00. The scope of this book is much wider than the title suggests, as fully one-quarter of the volume is devoted to biologic and therapeutic effects and miscellaneous applications. The authors have collected a n immense amount of material, which for the most part is presented in the form of brief abstracts of the original papers without comment or discussion. There is evidence of hasty preparation and frequent repetitions occur, which is not surprising considering the enormous number of papers reported. The chief fault of the work is that there is little or no attempt a t classification or criticism. The subjects treated include: Nature of ultra-violet rays and the sources which produce them; mercury arc lamps of various types; protective glasses and filters; observations on photochemical mechanism; reactions of gases in ultra-violet rays; various photochemical and photolytic reactions; the effect of the rays on halogenation reactions; photosynthesis and the formation of carbohydrates and proteins from atmospheric gases; sterilization by ultra-violet rays; biological and therapeutical applications; and miscellaneous observations. I n the chapter on mercury arc lamps sufficient credit is not given t o Arons, who constructed a mercury arc very similar to the Cooper-Hewitt lamp in 1892. I saw this lamp in operation in Arons’ laboratory when I was a student in the University of Berlin in 1895. It was a glass tube about 4 feet long with mercury electrodes and was started by tilting. Some early experiments which I made between 1901 and 1910 and demonstrated at the Royal Institution in London in 1911 appear to have escaped the notice of more recent workers, though they appeared in various scientific publications a t the time. I n this lecture the photography of flowers and other objects by ultra-violet light (quartz lens coated with silver) was described. This the authors have attributed t o Michaud and Tristan. An apparatus attributed t o Andrews for producing ultra-violet light by focal isolation by quartz lenses was described in this lecture and used for the production of phosphorescent effects. It was first used in collaboration with Rubens for the isolation of the longest heat waves known a t t h e time (1910) and is described and illustrated in my “Physical Optics.” The experiment showing t h a t white zinc oxide comes out black (pictured on page 325 and attributed to Nelson and Rundle, 1923) will also be found in the lecture. I n this same lecture the suggestion was made that the ultra-violet rays might prove useful in detecting forgeries, and in the following year I showed that alterations made in documents by chemical ink erasers coul&be
detected in this way, and photographs of such alterations were published in various journals a t the time. In the case of a mortgage submitted by the court in Baltimore the missing words in the document were brought out in the photograph. This use of the rays has been rediscovered and described repeatedly by other investigators. The authors make no mention of the high-power ultra-violet lamp developed during the war-which I have shown in numerous lectures-by which the entire audience in a large auditorium can be rendered phosphorescent in a perfectly dark room; this lamp has been popularized by its employment on the stage in connection with phosphorescent costumes. I n spite of these faults the book will be found of value by many who are working with ultra-violet rays, as a ready means of finding out what has been done on the subject. R. WOOD
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Tables and Graphs for Facilitating the Computation of Spectral Energy Distribution by Planck’s Formula. BY M. KATHERINE FREHAFER AND &ESTER L. SNOW. Bureau Of Standards Miscellaneous Publication 56. 7 sheets. 48 X 60 cm. Superintendent of Documents, Government Printing Office, Washington, D. C., 1925. Price, 35 cents. Sheet 1 is devoted to a brief discussion of the Planck formula and the values of the constants used in the computations. Sheets 2 to 6 plot the relative energy distribution a t 10 mp intervals from 400 to 720 mp and from 1000° t o 2P,0OO0 K. The energy a t 560 m p is taken as 100, and the maximum error of the plots is about 0.33 per cent. Sheet 7 is devoted t o tables which give the energy distribution a t fixed temperature intervals. “It has been shown t h a t a number of the ordinary illurninants have a spectral energy distribution t h a t approximates very closely that of a Planckian radiator.” If the illuminant can be matched in color with a black body, then the temperature of the black body is by definition the color temperature of the illuminant. This temperature is not difficult t o determine with suitable equipment, and the spectral distribution of the illuminant can be at once recorded by reading from the charts t h e energy values a t the given temperature. The charts will very greatly decrease the labor involved in making such calculations. MERLERANDALL Cellulose Ester Varnishes. BY F. SPROXTON. 178 pages. D. Van Nostrand Co., New York, 1925. Price, $4.50. For nearly fourteen years Warden’s two volumes on nitrocellulose have been the only textbook on the subject in the English language. These volumes, and a more recent one on cellulose acetate, while usually not considered as particularly interesting reading, are a faithful compilation of all available information essentially unedited, and in the field constitute a sort of cursive Beilstein. It has taken developments of note to cause an author to have the temerity t o bring forth a new work on the cellulose esters. These developments have not been lacking in recent times, particularly in the United States, where a vast business in pyroxylin automobile and furniture finishes has followed the appearance of low-viscosity nitrocellulose. In other countries the development has also been considerable, especially in the case of cellulose acetate for airplane dope. During the war there was naturally a decided improvement in the manufacture of guncotton, which is applicable to all nitrocellulose. Clearly, the time is ripe for new works on the cellulose esters and their application t o industry. Sproxton’s book is written in thoroughly interesting style, and in it a distinctly successful attempt has been made to evaluate the various processes and materials considered. It is modern and in every way a scientific treatise. The writer has clearly set forth the principles underlying the behavior of the cellulose esters. The development of the theory of what various solvents have in common (page 68) is particularly interesting and enlightening. Throughout the book the two commercial esters, the nitrate and the acetate, are considered as parallel materials with closely similar properties, differing only as might be expected from the difference in constitution.
